CN115244430A

CN115244430A - Optical component

Info

Publication number: CN115244430A
Application number: CN202180019793.XA
Authority: CN
Inventors: 梅泽朋一
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2020-03-25
Filing date: 2021-02-10
Publication date: 2022-10-25
Anticipated expiration: 2041-02-10
Also published as: WO2021192695A1; JPWO2021192695A1

Abstract

The present invention provides an optical component, which comprises: a single-layer substrate having a plurality of through holes for transmitting light; and an antireflection structure formed on at least a part of an inner wall surface of the through hole and including a plurality of grooves in a stripe shape.

Description

Optical component

Technical Field

The present invention relates to an optical component having a plurality of through holes through which incident light is emitted as parallel light.

Background

An optical component having a plurality of through holes for emitting incident light as parallel light is known. The optical member is a member in which a plurality of through holes penetrating in the thickness direction of a flat plate-like substrate are provided, and is also called a porous plate or the like. In the optical member, for example, a plurality of through holes are two-dimensionally arranged at equal intervals, and one surface of an arrangement surface on which the through holes are arranged becomes an incident surface and the other surface becomes an output surface.

Jp 2004-133308 a describes a transfer device that has the above optical member and transfers an image displayed on a liquid crystal display to a photosensitive recording medium by light from a light source. In the transfer device, the optical member is disposed between the liquid crystal display and the light source in a posture in which an incident surface, which is one surface of the arrangement surface of the through holes, faces an image display surface of the liquid crystal display, and light from the light source is incident on the optical member. The optical member collimates the incident light through each through hole and emits the collimated light as substantially parallel light. The parallel light emitted from the optical member is incident on the liquid crystal display, modulated by light of an image of the liquid crystal display, and irradiated to the photosensitive recording medium, thereby exposing the photosensitive recording medium to light. Thereby, the image displayed on the liquid crystal display is transferred to the photosensitive recording medium.

An optical component described in japanese patent application laid-open No. 2004-133308 is manufactured by stacking a plurality of thin plates in which a plurality of holes are formed so that the holes are aligned. The holes of the thin plates are laminated to form through holes penetrating the optical member having the laminated structure in which the thin plates are laminated.

The inner wall surface of the through hole of the optical member is black-coated, and most of the components incident on the inner wall surface while traveling obliquely among the light incident on the through hole of the optical member are absorbed, and the straight components traveling straight in the depth direction of the through hole (corresponding to the thickness direction of the flat plate-like substrate) are transmitted through the through hole and emitted.

Further, japanese patent application laid-open No. 2011-85612 relates to an image display device that limits an angle of view, and discloses a plate-shaped optical member called a Micro louver (Micro shutter) that limits a range of an emission direction of transmitted light. The microlouver is a member that substantially collimates light from a liquid crystal display device and emits the light, and has the same function as the optical member. The ultra-fine louver includes a plurality of transparent portions and a light absorbing layer provided so as to surround each of the transparent portions. Among the light incident on the transparent part, part of the oblique light component obliquely traveling and incident on the light absorption layer is absorbed, and the straight component straight traveling in the thickness direction of the transmission part is transmitted through the transmission part and emitted.

In the case of manufacturing a super fine louver described in japanese patent application laid-open publication No. 2011-85612, first, a transparent photosensitive resin formed in a thin plate shape is pattern-exposed, and the exposed pattern is developed, thereby forming a plurality of transparent portions arranged at intervals. Then, a black curable resin is filled in the gap between the transparent portions to form a light absorption layer. Thus, a micro louver in which a plurality of transparent portions are arranged at intervals is manufactured.

Disclosure of Invention

Technical problem to be solved by the invention

In the super fine louver described in japanese patent application laid-open publication No. 2011-85612, a part of an oblique light component in light incident on the transparent portion is absorbed by the light absorbing layer, but an antireflection structure is not formed between the transparent portion and the light absorbing layer. If the oblique light component is reflected at the interface between the transparent portion and the light absorbing layer, it is not absorbed by the light absorbing layer, and the oblique light component is emitted from the transparent portion. Since the oblique light component is not favorable for collimation of the incident light, it is desirable to reduce as much as possible. In particular, as the pixel size and the pixel pitch become smaller with higher pixelation of an image, the influence of the oblique light component on the image quality becomes larger, and thus the necessity of suppressing the oblique light component becomes higher.

On the other hand, as described above, the through-hole of the optical member described in japanese patent application laid-open No. 2004-133308 is formed by laminating a plurality of thin plates in which a plurality of holes are formed by photolithography. When the holes are formed in the respective thin plates by photolithography, a side etching phenomenon occurs, and therefore, tapered protrusions are formed on the inner wall surfaces of the holes in the respective thin plates. Therefore, in the optical member having the laminated structure obtained by laminating a plurality of thin plates with the positions of the respective holes being aligned, the projections having the tapered shape corresponding to the number of the respective thin plates are formed on the inner wall surface of the through hole, thereby forming the unevenness. The unevenness has an effect of preventing reflection of an oblique light component on the inner wall surface of the through hole.

However, in the laminated structure such as the optical member of japanese patent application laid-open No. 2004-133308, the effect of preventing the reflection of the oblique light component is obtained by the irregularities formed on the inner wall surface, but on the other hand, it is necessary to align the positions of the holes of the respective thin plates in the manufacturing process. Therefore, as the pixel size and the pixel pitch are smaller, alignment becomes more difficult, and the yield may be lowered.

The present invention has been made in view of such circumstances, and an object thereof is to provide an optical component that can emit parallel light with a suppressed oblique light component with a higher yield than conventional optical components.

Means for solving the technical problems

The optical member of the present invention is an optical member including a single-layer substrate having a plurality of through holes for transmitting light, and an antireflection structure formed on at least a part of an inner wall surface of the through holes and including a plurality of grooves in a stripe shape.

In the optical member of the present invention, the grooves preferably include at least a plurality of first grooves in a stripe shape along the depth direction of the through-hole.

Alternatively, in the optical member of the present invention, the grooves preferably include at least a plurality of second grooves in a stripe shape in a direction intersecting with a depth direction of the through-hole.

In the optical member according to the present invention, the groove preferably includes a plurality of second grooves in a stripe shape in a direction intersecting with a depth direction of the through hole in addition to the first groove.

In the optical member of the present invention, it is preferable that the average period of the plurality of first grooves is different from the average period of the plurality of second grooves.

In the optical member of the present invention, the substrate is preferably an opaque material.

In the optical member of the present invention, it is preferable that the aspect ratio, which is the ratio of the depth of the through-hole to the size of the opening, is greater than 20.

In the optical member of the present invention, it is preferable that the size of the opening of the through hole is larger than the average period of the grooves.

In the optical member of the present invention, the size of the opening of the through hole is preferably 5 to 100 μm.

In the optical member of the present invention, it is preferable that the optical member includes a plurality of through holes and that the arrangement of the plurality of holes is square.

In the optical member of the present invention, the difference between the transmittance of the substrate to light and the transmittance of the through hole to light is preferably 70% or more.

In the optical member of the present invention, the through hole may be filled with a transparent material.

In the optical member of the present invention, the groove is preferably provided at least one opening end of the through hole.

In the optical member of the present invention, the antireflection structure is preferably an irregular structure.

In the optical member of the present invention, it is preferable that the fine uneven structure is formed on at least one of the front surface and the back surface of the substrate at a portion other than the opening of the through hole.

In the optical member of the present invention, the fine uneven structure is preferably an irregular structure.

In the optical member of the present invention, it is preferable that the substrate is provided with a protective layer on a surface on which the fine uneven structure is formed.

In the optical member of the present invention, the groove depth of the antireflection structure is preferably deeper than the recess depth of the fine uneven structure.

In the optical member of the present invention, the substrate is preferably silicon.

Effects of the invention

According to the present invention, it is possible to provide an optical component which can be manufactured with high yield and can emit parallel light with suppressed oblique light components.

Drawings

Fig. 1 is a perspective view of an optical component according to an embodiment.

Fig. 2 is a schematic sectional view of the optical member shown in fig. 1, taken along line II-II.

Fig. 3 is an enlarged view of an inner wall surface of an example of the through-hole.

Fig. 4 is an enlarged view of an inner wall surface of another example of the through hole.

Fig. 5 is an enlarged view of an inner wall surface of another example of the through hole.

Fig. 6 is an explanatory view of the optical member.

Fig. 7 is a cross-sectional view of an optical component according to a design modification.

Fig. 8 is a sectional view of an optical component according to another design modification.

Fig. 9 is a diagram for explaining a use example of the optical member.

Fig. 10 is a diagram illustrating steps of a method for manufacturing an optical member.

Fig. 11 is a diagram showing a process for producing a substrate having a fine uneven structure.

Fig. 12 is a view showing a step of the penetration treatment of the fine uneven layer containing the hydrate of alumina.

Fig. 13 is a diagram showing an example of a mask forming process.

Fig. 14 is a diagram showing another example of the mask forming step.

Fig. 15 is a view showing an inner wall surface of the recess.

Fig. 16 is a diagram for explaining an etching process.

Fig. 17 is a diagram for explaining an etching process.

Fig. 18 is a view showing another example of the inner wall surface of the recess.

Fig. 19 is a scanning microscope photograph showing a part of the structure produced in the experimental experiment.

Fig. 20 is a scanning microscope photograph showing an enlarged portion of the structure shown in fig. 19.

Fig. 21 is a scanning microscope photograph showing a further enlarged portion of the structure shown in fig. 20.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the film thickness of each layer or the ratio thereof is drawn while being appropriately changed for the sake of visual recognition, and this does not necessarily reflect the actual film thickness or ratio. In the present specification, the numerical range expressed by the term "to" refers to a range including numerical values before and after the term "to" as a lower limit value and an upper limit value.

The optical member of the present invention includes: a single-layer substrate having a plurality of through holes through which light passes; and an antireflection structure formed on at least a part of an inner wall surface of the through hole and including a plurality of grooves in a stripe shape.

Fig. 1 is a perspective view of an optical component 1 according to an embodiment, and fig. 2 is a view schematically showing a cross section of the optical component 1 shown in fig. 1 taken along line II-II. The optical component 1 includes: a single-layer substrate 10 having a plurality of through holes 21 for transmitting light; and an antireflection structure 25 formed on at least a part of the inner wall surface 21b of the through hole 21 and including a plurality of stripe-shaped grooves 24. The through hole 21 is provided to penetrate from the one surface 10a to the other surface 10b of the substrate 10, and the substrate 10 has openings of the through hole 21 in the one surface 10a and the other surface 10 b. The antireflection structure 25 is constituted by an uneven structure constituted by a plurality of stripe-shaped grooves 24 formed on the inner wall surface 21b, that is, projections between the recesses and the grooves 24. In the present optical component 1, the one surface 1a and the other surface 1b of the optical component 1 coincide with the one surface 10a and the other surface 10b of the substrate 10.

The term "single-layer substrate" means that the substrate 10 provided with the through-holes 21 is a single layer, and does not mean that the substrate 10 is formed by laminating a plurality of layers, and of course does not mean that the optical member 1 is a single layer. Therefore, it is not excluded that the entire optical member 1 is formed of a plurality of layers by providing a protective layer on the surface of the substrate 10 or applying coating. In the optical component 1, since the substrate 10 provided with the through-holes 21 is a single layer, the optical component as described in japanese patent application laid-open No. 2004-133308 can be manufactured with a higher yield than the case where the optical component is formed by laminating a plurality of thin plates each having a plurality of holes formed by photolithography.

The "stripe-shaped groove" is a groove continuously formed in one direction (in the example shown in fig. 2, the depth direction Z) with respect to a portion of the inner wall surface 21b recessed from the most convex surface on the central axis side of the through-hole 21, and the length of the groove in the one direction is 3 times or more the width of the groove in the direction orthogonal to the one direction. The "most convex surface" on the central axis side of the through hole 21 means, for example, that when the inner wall surface 21b immediately after the through hole 21 is formed is processed to form a stripe-shaped groove, an unprocessed surface remaining adjacent to the stripe-shaped groove in the inner wall surface 21b becomes the "most convex surface". The groove 24 may have a width that does not vary in the longitudinal direction, or may have a width that varies in the longitudinal direction. When the width of the groove 24 varies, the width of the groove 24 for comparison with the length of the groove 24 is set to the width of the widest portion.

In fig. 2, the plurality of stripe-shaped grooves 24 constituting the antireflection structure 25 indicate stripe-shaped grooves 24 extending in the depth direction Z of the through-hole 21, as an example. Fig. 3 to 5 schematically show examples of the shape of the stripe-shaped groove 24. Fig. 3 to 5 are perspective views showing a part of the inner wall surface 21b of the through hole 21, and the vertical direction of the drawing is made to coincide with the depth direction Z of the through hole 21.

Fig. 3 is an enlarged view of the groove 24 shown in fig. 2. The grooves shown in fig. 3 are a plurality of first grooves 24a in a stripe shape along the depth direction Z of the through-hole 21. In the present specification, the "stripe-shaped first grooves 24a extending in the depth direction of the through-hole 21" is not limited to grooves extending in a direction parallel to the depth direction shown in fig. 3, and includes grooves extending in a direction inclined within ± 30 ° with respect to the depth direction. The plurality of first grooves 24a may be parallel to each other or may not be parallel to each other. The width of the first groove 24a may be changed to be narrower as it goes toward the depth direction, or may be changed to be wider. The distances P1 between the first grooves 24a adjacent to the concave depth d1 of the first grooves 24a may be the same or different. The average of the distances P1 between the adjacent first grooves 24a is referred to as the average period of the first grooves 24a.

The plurality of stripe-shaped grooves 24 constituting the antireflection structure provided in the optical member 1 are not limited to the first grooves 24a extending in the depth direction Z as described above. As shown in fig. 4, the plurality of second grooves 24b may be stripe-shaped in a direction intersecting the depth direction Z. The second groove 24b shown in fig. 4 is a stripe-shaped groove extending in a direction orthogonal to the depth direction Z and extending in a direction parallel to the first surface 10a of the substrate 10. However, the second groove 24b is not limited to a groove perpendicular to the depth direction Z as long as it is a direction intersecting the depth direction Z. Like the first grooves 24a, the plurality of second grooves 24b may be parallel to each other or may not be parallel to each other. The width of the second groove 24b may also vary in the direction in which the groove 24b extends. The average of the distances P2 between the second grooves 24b adjacent to the concave depth d2 of the second grooves 24b is referred to as the average period of the second grooves 24b.

As shown in fig. 5, the plurality of stripe-shaped grooves 24 constituting the antireflection structure provided in the optical member 1 may include a combination of a plurality of first grooves 24a in a stripe shape extending in the depth direction of the through-hole 21 and a plurality of second grooves 24b in a stripe shape extending in the direction intersecting with the depth direction, in a grid shape. In fig. 5, the average period of the first grooves 24a is substantially the same as the average period of the second grooves 24b, but the average periods of the first grooves 24a and the second grooves 24b may be different.

The distance P1 between the first grooves 24a and the distance P2 between the second grooves 24b may be regular or irregular. However, the irregular distance between the grooves is preferable because the interference of light can be suppressed.

The stripe-shaped groove 24 is a concept of a groove formed on the inner wall surface including the first groove 24a and the second groove 24b, and in the present specification, when simply referred to as the groove 24, both the first groove 24a and the second groove 24b are referred to.

The average period of the stripe-shaped grooves 24 was measured by cutting the substrate 10 at a position where the inner wall surface 21b of the through-hole 21 could be observed, and observing the inner wall surface 21b from the front using a Scanning Electron Microscope (SEM). In the SEM image, in the region where the striped grooves 24 were observed, the distances between the grooves 24 at arbitrary 10 positions were measured, and the value obtained by averaging the measured distances was defined as the average period of the grooves 24. The average period of the grooves 24 in the stripe shape is, for example, several nm to 1 μm, but may be 10nm to 800nm, 10nm to 400nm, or 10nm to 200nm. The average period preferably differs depending on the wavelength λ of light to which the present member is applied, and the average period is preferably equal to or less than the used wavelength λ, and more preferably equal to or less than half the used wavelength (equal to or less than λ/2). For example, in order to obtain an antireflection effect in the visible light range of 380nm to 780nm in wavelength, the average period of the stripe-shaped grooves 24 is preferably 380nm or less, and more preferably 190nm or less which is a half of the shortest wavelength 380 mm. The depth of the groove 24 is, for example, several nm to 1 μm, but may be 10nm to 800nm, 10nm to 400nm, or 10nm to 200nm. In addition, from the viewpoint of more effectively obtaining the antireflection, when the wavelength λ is used, the depth of the groove 24 is preferably λ/4 or more, and more preferably λ/2 or more. For example, in order to obtain an antireflection effect in the visible light range of 380nm to 780nm in wavelength, the depth of the groove 24 is preferably 195nm or more, which is λ/4 of the longest wavelength of 780nm, and more preferably 390nm or more, which is λ/2 or more. Here, the depth of the groove 24 is a distance in the groove depth direction from the most recessed portion of the groove 24 to the position of the convex portion between the grooves 24.

The optical member 1 can be used as a collimator that emits incident light as parallel light, for example. As schematically shown in fig. 6, of the light incident from the one surface 1a of the optical member 1, the straight component L1 incident on the through-hole 21 and traveling in the depth direction thereof passes through the through-hole 21 directly and is emitted from the other surface 1b of the optical member 1. On the other hand, the oblique light component L2 obliquely incident on the through hole 21 is incident on the inner wall surface 21b of the through hole 21. Since the antireflection structure 25 including the plurality of grooves 24 in a stripe shape formed in the inner wall surface 21b is provided, the oblique light component L2 incident on the inner wall surface 21b is hardly reflected. When the inner wall surfaces 21b of the through-holes 21 do not have the antireflection structure 25, at least a part of the oblique light component L2 is reflected 1 or more times on the inner wall surfaces 21b and is emitted from the through-holes 21, as shown by a broken line in fig. 6. According to the present optical component 1, reflection of light incident on the inner wall surface 21b can be suppressed, and as a result, light incident obliquely as incident on the inner wall surface 21b of the through hole 21 can be suppressed from being emitted from the other surface 1b of the optical component 1. Therefore, according to the optical member 1, parallel light in which the oblique light component in the incident light is sufficiently suppressed can be emitted.

The difference between the transmittance of the substrate 10 for the collimated light and the transmittance of the through-hole 21 is preferably 70% or more. The transmittance of the substrate 10 refers to the transmittance of light in a portion other than the through-hole 21 of the substrate. When the difference between the transmittance of the substrate 10 and the transmittance of the through-hole 21 is 70% or more, the emitted light as parallel light can be efficiently extracted.

Preferably, the substrate 10 is an opaque material. If the substrate 10 is made of an opaque material, light incident on the one surface 10a and the other surface 10b of the substrate 10 and light incident on the inner wall surfaces 21b of the through holes 21 are absorbed, and therefore, the collimation can be further improved while suppressing the mixing of light between the through holes 21. Here, opaque means that the transmittance of light with respect to a collimated object is less than 30%. The light to be targeted is mainly visible light, but may be infrared light or ultraviolet light. As a material opaque to visible light, for example, silicon can be cited. As for the silicon wafer applicable to the substrate 10, it can be easily obtained and easily handled.

When at least one of the first surface 10a and the second surface 10b of the substrate 10 and the inner wall surface 21b of the through hole 21 are coated with black, light incident on the first surface 10a and the second surface 10b of the substrate 10 and the inner wall surface of the through hole 21 is absorbed. Therefore, even if the uncoated substrate itself is a transparent material, the substrate 10 becomes substantially the same in transmittance as the opaque material by applying black coating. The through-hole 21 may be a cavity, or the through-hole 21 may be filled with a transparent material.

As shown in the through-holes 21 at both ends of the plurality of through-holes 21 shown in fig. 2, the stripe-shaped groove 24 may be provided over the entire region in the depth direction, or may be provided at least partially as shown in the other through-holes 21. When the groove 24 is locally provided, the through hole 21 may be provided in a region occupying 1% to 50% of the depth D in the depth direction, for example. In the case where the groove 24 is provided locally, it may be provided at any position in the depth direction of the through hole 21. The groove 24 may be provided at an opening end in the depth direction of the through hole 21, or may be provided inside the opening end. The portion to be provided is not limited to one place, and may be provided at a plurality of places in a dispersed manner. Here, the open end refers to an opening including the through hole 21 located on the one surface 10a or the other surface 10b of the substrate 10, and is in a range of 1% of the depth D from the opening. In addition, the average period of the stripe-shaped grooves 24 was measured in the region where the grooves 24 were formed.

When the groove 24 is provided on at least a part of the inner wall surface 21b of each through-hole 21, reflection of an oblique light component in light incident into the through-hole 21 from one end of each through-hole 21 on the inner wall surface 21b can be suppressed at least partially. Further, an oblique light component traveling in a direction greatly inclined with respect to the depth direction of the through hole 21 is incident on the inner wall surface 21b at the opening end of the through hole 21. Therefore, it is preferable to provide the groove 24 at least at the opening end because reflection of a greatly inclined oblique light component can be suppressed, and collimation can be promoted.

The aspect ratio D/a, which is the ratio of the depth D of the through-hole 21 to the size a of the opening, is preferably greater than 20. The through-hole 21 has a tapered shape, and when the size of the opening in the one surface 10a of the substrate 10 is different from the size of the opening in the other surface 10b, the size of the smaller opening is defined as the size a of the opening of the through-hole 21. The size of the opening is defined as the equivalent circle diameter of the opening. If the aspect ratio of the through-hole 21 is larger than 20, most of the oblique light component is incident on the inner wall surface 21b and absorbed in the through-hole 21, and therefore, collimation of light can be sufficiently improved.

The size of the opening of the through-hole 21 is preferably larger than the average period of the groove 24. The size of the opening of the through-hole 21 is, for example, 5 to 1000 μm, preferably 5 to 500 μm, and more preferably 5 to 100 μm.

In the optical component 1, the fine uneven structure 30 having the antireflection function is formed on the portion of the one surface 10a which is one of the front surface and the back surface of the substrate 10 excluding the opening of the through hole 21.

Since the fine uneven structure 30 has the antireflection function, in the optical member 1 of the present example, reflection of light incident on the portion of the one surface 10a other than the opening of the through hole 21 can be suppressed. The fine uneven structure 30 may include regularly arranged unevenness, and preferably an irregular structure. If the fine uneven structure is an irregular structure, interference of light can be suppressed. Here, the "irregular structure" means, for example, a structure in which at least one of the size, shape, and arrangement pitch of the convex portions 32 is irregular, such as a structure in which the size or shape of the convex portions 32 is different, or an arrangement pitch that is a distance between a plurality of adjacent convex portions 32 is not uniform. The average period of the fine uneven structure 30 is approximately 1 μm or less. Here, the average period of the fine uneven structure 30 refers to an average of distances between the plurality of projections 32. The distance between the convex portions 32 means, when attention is paid to one convex portion 32, the distance from the convex portion located closest to the convex portion 32, and is the distance between the apexes of the two convex portions. Specifically, in a Scanning Electron Microscope (SEM) image of the surface of the fine uneven structure 30, the distances between the convex portions 32 at arbitrary 10 positions are measured, and the value obtained by averaging the measured distances is defined as the average period of the fine uneven structure 30. The average period of the fine uneven structure 30 is, for example, several nm to 1 μm, but may be 10nm to 800nm, 10nm to 400nm, or 10nm to 200nm. The average period preferably differs depending on the wavelength λ of light to which the present member is applied, and the average period is preferably equal to or less than the used wavelength λ, and more preferably equal to or less than half the used wavelength (equal to or less than λ/2). For example, in order to obtain an antireflection effect in the visible light range of 380nm to 780nm in wavelength, the average period of the stripe-shaped grooves 24 is preferably 380nm or less, and more preferably 190nm or less which is a half of the shortest wavelength 380 mm. The unevenness e of the fine uneven structure 30 is, for example, several nm to 1 μm, but may be 10nm to 800nm, 10nm to 400nm, or 10nm to 200nm. In addition, from the viewpoint of more effectively obtaining the antireflection, when the wavelength λ is used, the uneven difference e of the fine uneven structure 30 is preferably λ/4 or more, and more preferably λ/2 or more. For example, in order to obtain an antireflection effect in the visible light range of 380nm to 780nm in wavelength, the depth of the groove 24 is preferably not less than 195nm, which is λ/4 of 780nm in the longest wavelength, and more preferably not less than 390nm, which is λ/2.

In addition, when the optical member 1 includes the fine uneven structure 30, the recess depth d (d 1, d 2) of the groove 24 of the antireflection structure 25 provided on the inner wall surface 21b of the through hole 21 is preferably deeper than the uneven difference e of the fine uneven structure 30. In the light incident from the one surface 10a of the optical member 1, the incident angle of the oblique light component incident on the inner wall surface 21b is generally larger than the incident angle of the light to the fine uneven structure 30. The larger the difference in the unevenness of the unevenness is, the higher the antireflection effect is with respect to light having a large incident angle. Therefore, by making the depth of the stripe-shaped concave portions formed on the inner wall surface 21b of the through-hole 21 deeper than the difference in the irregularities of the fine uneven structure 30, a sufficient antireflection effect can be obtained with respect to an oblique light component incident at a large incident angle.

In the optical member of the present invention, the fine uneven structure 30 is not essential, but it is more preferable that the fine uneven structure 30 is provided on at least one of the front surface and the back surface of the substrate. By providing the fine uneven structure 30 on at least one of the front surface and the back surface of the substrate, reflection of light incident on a portion other than the through-hole can be suppressed as described above. The reflected light on at least one of the front surface and the back surface becomes a noise component with respect to the parallel light transmitted through the through hole 21. Therefore, by suppressing the reflected light by the fine uneven structure 30, it is possible to reduce the noise component from mixing into the parallel light passing through the through hole 21.

Fig. 7 and 8 are schematic cross-sectional views of

optical members

2 and 3 according to another embodiment. The same elements as those of the optical component 1 of fig. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

The optical member 2 has a fine uneven structure 30 formed not only on the one surface 10a but also on the other surface 10b of the substrate 10 except for the opening of the through-hole 21. As described above, by providing the fine uneven structure 30 having the antireflection function on both the front surface and the back surface of the substrate 10, it is possible to suppress reflection of light incident on portions other than the opening of the through hole 21 on both the front surface and the back surface of the substrate 10. Therefore, compared to the case where the fine uneven structure 30 is provided on one of the front surface and the back surface, it is possible to reduce the noise component from mixing into the parallel light transmitted through the through-hole 21.

As another example of the optical member 3 shown in fig. 8, the optical member of the present invention may further include a protective layer 35 on the surface of the fine uneven structure 30. By providing the protective layer 35, the fine uneven structure can be protected, and the durability can be improved. As the protective layer 35, a transparent hard coat film is preferable, and for example, a PET (Polyethylene terephthalate) film or the like can be used.

Fig. 9 shows an example of the application of the optical member of the present invention. As shown in fig. 9, the optical member 3 of the present invention can be used in a transfer device 100 for transferring an image displayed on a liquid crystal display 101 to a photosensitive recording medium 102. Fig. 9 shows a case where the optical component 3 is provided, but the optical component 1 shown in fig. 6 or the optical component 2 shown in fig. 7 may be used. In the transfer device 100, the optical member 3 is disposed between the liquid crystal display 101 and the photosensitive recording medium 102 in a posture in which the one surface 10a of the substrate 10 provided with the through hole 21 faces the image display surface of the liquid crystal display 101, and light from the liquid crystal display 101 is incident thereon. The optical member 3 collimates light incident on the optical member 3 through the through holes 21 and emits the collimated light as substantially parallel light. The photosensitive recording medium 102 is subjected to surface exposure by the light emitted from each through hole 21. Thereby, the image displayed on the liquid crystal display 101 is transferred to the photosensitive recording medium 102.

The size and arrangement pitch of the through holes 21 are preferably formed to correspond to the size and pixel pitch of the pixels of the liquid crystal display 101. Therefore, when the pixels of the liquid crystal display 101 are square-arrayed, it is preferable that the array of the through holes 21 in the substrate 10 is also square-arrayed. In particular, if the pixels of the liquid crystal display 101 correspond to the through holes 21 in a 1.

In the optical member 3, since the fine uneven structure 30 is provided on the surface 10a on which light from the liquid crystal display 101 enters, reflection of light entering the surface 10a other than the through-hole 21 on the surface 10a is suppressed, and the entered light is almost absorbed by the substrate 10. On the other hand, the straight component of the light incident on the through-hole 21 from the one surface 10a of the substrate 10 is emitted directly from the other surface 10b and is irradiated to the photosensitive recording medium 102 through the protective layer 35. On the other hand, the oblique light component of the light incident on the through hole 21 is incident on the inner wall surface 21b inside the through hole 21. Since the optical member 3 includes the antireflection structure 25 on the inner wall surface 21b of the through hole 21, the oblique light component incident on the inner wall surface 21b is not reflected and is almost absorbed by the substrate 10. Further, although there is a case where a part of the light emitted from the other surface 10b of the substrate 10 and irradiated to the photosensitive recording medium 102 is reflected by the photosensitive recording medium 102 and returned to the optical member 3 side, since the optical member 3 is also provided with the fine uneven structure 30 on the other surface 10b of the substrate 10, the light incident on the other surface 10b can be prevented from being reflected, and the light can be prevented from being reflected again and directed to the photosensitive recording medium. Therefore, the optical member 3 can guide only the straight component of the light emitted from the liquid crystal display 101 to the photosensitive recording medium 102, and an image with less bleeding and high transfer accuracy can be obtained.

In the optical member 3, the protective layer 35 is provided on the other surface 10b of the substrate 10 facing the photosensitive recording medium 102 to protect the fine uneven structure 30, and therefore, damage to the fine uneven structure 30 when the photosensitive recording medium 102 comes into contact with the optical member 3 can be prevented.

Next, a method for manufacturing an optical member of the present invention will be described. Here, an example of a manufacturing method for manufacturing the optical member 2 will be described with reference to fig. 10 to 18. As shown in fig. 10, the manufacturing process includes a substrate preparation process (ST 1), a mask formation process (ST 2), a dry etching process (ST 3), and a mask removal process (ST 4).

< substrate preparation Process >

First, as shown in ST1 of fig. 10, a substrate 10 having a fine uneven structure 30 with an average period of 1 μm or less on one surface 10a is prepared. Fig. 11 shows an example of a substrate preparation step. An example substrate preparation process includes: a step (ST 12) of forming an aluminum-containing thin film on one surface of the substrate 9 to be processed; a step (ST 13) of subjecting the aluminum-containing thin film to a hot water treatment to convert the thin film into a fine uneven layer containing an alumina hydrate; a step (ST 14) of etching one surface of the substrate 9 from the fine uneven layer side; and a step (ST 15) of removing the fine uneven layer.

First, as shown in ST12 of fig. 11, an aluminum-containing thin film 50 (hereinafter, referred to as Al-containing thin film 50) is formed on one surface of the substrate 9.

The Al-containing thin film 50 is, for example, a thin film composed of any one of aluminum, acidified aluminum, aluminum nitride, and an aluminum alloy, but may be a material that is changed to a fine uneven layer containing a hydrate of alumina such as boehmite by hot water treatment in a subsequent step. The "aluminum alloy" refers to a compound or a solid solution containing at least 1 kind of element such as silicon (Si), iron (Fe), copper (Cu), manganese (Mn), magnesium (Mg), zinc (Zn), chromium (Cr), titanium (Ti), and nickel (Ni), and containing aluminum as a main component. In the Al-containing thin film 50, the compositional ratio of aluminum to all metal elements is preferably 80 mol% or more from the viewpoint of forming an uneven structure.

The thickness of the Al-containing thin film 50 may be set according to a desired thickness of the fine uneven layer obtained in the subsequent step. For example, the thickness of the Al-containing thin film 50 is 0.5 to 60nm, preferably 2 to 40nm, and particularly preferably 5 to 20nm.

The method for forming the Al-containing thin film 50 is not particularly limited. For example, a general film formation method such as a resistance heating vapor deposition method, an electron beam vapor deposition method, or a sputtering method can be used.

Next, as shown in ST13 of fig. 11, in the hot water treatment step, the Al-containing thin film 50 is subjected to hot water treatment. For example, as shown in ST13 of fig. 11, pure water 56 in a container 55 is heated by a hot plate 58, and the entire substrate 9 to be processed on which the Al-containing thin film 50 is formed is immersed in warm water. By performing the hot water treatment, as shown in ST14 of fig. 11, the Al-containing thin film 50 can be changed to the fine uneven layer 52 containing a hydrate of alumina. The fine uneven layer 52 has a plurality of convex portions and a plurality of concave portions formed in irregular shapes and arrangements. The size of the convex portions of the uneven structure layer and the average distance between the convex portions (i.e., the average period of the uneven portions) can be controlled by the material of the Al-containing thin film 50, the thickness of the film, and the conditions of hot water treatment, but the average period is approximately 1 μm or less.

Here, the "hot water treatment" refers to a treatment in which hot water is applied to the aluminum-containing thin film. The hot water treatment is, for example, a method of immersing the laminate having the aluminum-containing thin film 50 formed thereon in water at room temperature and then boiling the water, a method of immersing the laminate in hot water maintained at a high temperature, a method of exposing the laminate to high-temperature steam, or the like. As described above, in the present embodiment, pure water 56 in container 55 is heated by hot plate 58 and immersed in warm water together with substrate to be processed 9. The time for immersing in the warm water and the temperature of the warm water can be appropriately set according to the desired concave-convex structure. The standard time is 1 minute or more, and particularly preferably 3 minutes or more and 15 minutes or less. The temperature of the warm water is preferably 60 ℃ or higher, and particularly preferably higher than 90 ℃. The treatment time tends to be shorter as the temperature is higher. For example, when a thin film containing aluminum with a thickness of 10nm is boiled in warm water at 100 ℃ for 3 minutes, an irregular uneven structure in which the distance between projections is 50nm to 300nm and the height of the projections is 50nm to 100nm can be obtained.

Then, as shown in ST15 of fig. 11, the substrate 10 having the fine uneven structure 30 on one surface 10a can be obtained by etching the surface of the substrate 9 on which the fine uneven layer 52 containing a hydrate of alumina is formed, with the etching gas G2 from the side of the fine uneven layer 52. When etching is performed from the surface of the fine uneven layer 52, the uneven shape of the surface of the fine uneven layer 52 gradually recedes due to dissolution erosion by etching, and the dissolution erosion acts on the surface of the substrate 9 in a form reflecting the uneven shape of the fine uneven layer 52. Thereby, the fine uneven structure 30 reflecting the form of the fine uneven layer 52 is formed on the surface of the substrate 9. The uneven shape "reflecting" the fine uneven layer 52 means a state of not requiring the position accuracy of the so-called transfer level of the convex or concave portion at the position corresponding to 1 of the convex or concave portion of the uneven shape but having a level of similarity to some undulations.

In this etching step, for example, reactive ion etching, reactive ion beam etching, or the like is preferably used. It is preferable to perform etching under the condition that the etching rate of the substrate 10 is higher than the etching rate of the fine uneven layer 52. As the etching gas G2 having a high etching efficiency with respect to the substrate 10, for example, a fluorine-based gas or a chlorine-based gas similar to the etching gas G1 can be given.

Before the etching step of the substrate 9 to be processed, it is preferable to perform a penetration treatment for etching the fine uneven layer 52 until at least a part of the surface of the substrate 9 to be processed is exposed. Specifically, as shown in fig. 12, after the fine uneven layer 52 is formed (ST 14), the fine uneven layer 52 is etched (ST 40), and the surface of the substrate 9 to be processed is exposed at least in a part of the concave portion of the fine uneven layer 52 (ST 41). In the penetration treatment, in order to effectively etch the fine uneven layer 52, the etching gas G3 having a high etching efficiency with respect to the alumina hydrate is used. As the etching gas G3, for example, argon (Ar) and trifluoromethane (CHF) are used ₃ ) Of (2) is used. Thereafter, in order to form the fine uneven structure 30 on the surface of the substrate 9 to be processed, as shown in ST42 of fig. 12, the surface of the substrate 9 to be processed is etched from the side of the fine uneven layer 52 using the etching gas G2, thereby obtaining the substrate 10 having the fine uneven structure 30 on one surface 10a (ST 1). By performing the penetration treatment, the time required for the etching step of the substrate can be significantly shortened, and therefore, the manufacturing efficiency of the entire manufacturing process can be improved.

The mask removal process preferably includes the use of sulfuric acid H ₂ SO ₄ With hydrogen peroxide H ₂ O ₂ A cleaning step of a mixture of (1) and (2) hydrogen peroxide sulfate such as SH-303 manufactured by Kanto Chemical Co. When hydrogen peroxide sulfate is used, the fine uneven layer 52 remaining after the etching step can be effectively removed.

The method for producing a substrate having a fine uneven structure on the surface is not limited to the above. Fine particles of Cr or the like are irregularly adhered to a flat plate-like substrate to be processed, and the substrate surface is etched using the particles as a mask, whereby a substrate having a fine uneven structure on the surface can be produced. A resin layer is formed on the surface of the substrate to be processed, the uneven pattern of the mold having the uneven pattern is pressed against the resin layer, the uneven pattern is transferred onto the resin layer, a mask made of the resin layer is formed on the surface of the substrate, and the surface of the substrate to be processed is etched using the resin layer as the mask, whereby a substrate having a fine uneven structure on the surface can be manufactured. However, as described above, according to the method of forming a fine uneven structure containing alumina hydrate, irregular fine unevenness of 1 μm or less can be easily produced, and therefore a substrate having a fine uneven structure can be efficiently produced.

< mask Forming Process >

Next, as shown in ST2 of fig. 10, in the mask forming step, a mask 42 having an opening pattern 41 is formed on the fine uneven structure 30.

The method and the mask material for forming the mask 42 in the mask forming step are not particularly limited, but the mask 42 is preferably made of an organic material. If an organic material is used, the mask 42 having a desired opening pattern can be formed by an easy method. Hereinafter, a method of forming the mask 42 using an organic material will be briefly described.

The mask forming step includes a photoresist coating step, a photoresist exposure step, and a photoresist developing step. As shown in ST21 of fig. 13, a positive photoresist 40 is applied to one surface 10a of the substrate 10. As shown in ST22 of fig. 13, an exposure mask 47 is disposed on the photoresist 40, and the portion 40a where the opening of the photoresist 40 is formed is irradiated with a laser beam L and exposed. After that, by developing the photoresist 40, only the exposed portion 40a of the photoresist 40 is dissolved to form an opening, and the mask 42 having the opening pattern 41 can be formed (ST 2).

Alternatively, the mask forming step may include a step of applying a resin layer and a step of transferring the uneven pattern to the resin layer. As shown in ST23 of fig. 14, a resin layer 46 made of a photocurable resin composition, for example, is applied to one surface 10a of the substrate 10. Then, as shown in ST24 of fig. 14, the uneven pattern surface is pressed against the resin layer 46 using a pressing mold 48 having an uneven pattern corresponding to the opening pattern 41 of the mask 42 to be formed, and the uneven pattern is transferred onto the resin layer 46. Thereafter, as shown in ST25 of fig. 14, the resin layer 46 is cured by irradiating the resin layer 46 with ultraviolet light 49, and then the imprint mold 48 is peeled off, whereby the mask 42 having the opening pattern 41 on the substrate 10 can be obtained (ST 2).

< Dry etching Process >

Thereafter, as shown in ST3 of fig. 10, in the dry etching step, the one surface 10a of the substrate 10 is subjected to dry etching using the etching gas G1 by using the mask 42 formed in the mask forming step. By this dry etching, the through-holes 21 corresponding to the opening pattern of the mask 42 are formed in the one surface 10a of the substrate 10.

In the dry etching step, reactive ion etching is preferable. In order to make the etching rate with respect to the substrate 10 larger than the etching rate with respect to the mask 42, it is preferable to use the etching gas G1 having high etching efficiency with respect to the substrate 10. Specifically, fluorine-based gas or chlorine-based gas may be mentioned. As the fluorine-containing gas, for example, trifluoromethane (CFH) can be used ₃ ) Or sulfur hexafluoride yellow (SF) ₆ ) As the chlorine-based gas, for example, chlorine gas (Cl) can be used ₂ )。

When the through-hole 21 is formed by dry etching on the substrate 10 having the fine uneven structure 30 on one surface 10a, as shown in fig. 15, a stripe-shaped groove 24 corresponding to the unevenness of the fine uneven structure 30 is formed in the inner wall surface 21b of the through-hole 21. Fig. 15 is a sectional view of a portion including one through hole 21 of the optical component 1. The inner wall surface 21b of the through-hole 21 is formed with a stripe-shaped groove 24 having a width substantially corresponding to the width of the convex portion 32 of the fine uneven structure 30 or the interval of the convex portions 32 and extending in the depth direction of the through-hole 21. In fig. 15, the portion indicated by gray hatching is a groove 24 which is recessed from the portion indicated by white. The width of the stripe-shaped groove 24 has a width almost corresponding to the width of the projection 32 or the interval of the projection 32 on the surface layer side in the depth direction, and gradually becomes narrower on the deep layer side.

The reason for forming the stripe-shaped grooves 24 as shown in fig. 15 is roughly due to the interaction between the plurality of projections 32 of the fine uneven structure 30 and the mask 42. The principle of forming the stripe-shaped groove 24 as shown in the figure will be described with reference to fig. 16 and 17. In fig. 16 and 17, the left side shows a state in which the mask 42 is formed on the fine uneven structure 30 on one surface of the substrate 10 before the dry etching step, and the right side shows a state in which the mask is removed after the dry etching step. In each figure, the upper view is a plan view of the structure viewed from above the convex portion 32, and the lower view is a side view.

First, the example of fig. 16 shows the following case: when the mask 42 is formed on the substrate 10, the entire plurality of projections 32 of the fine uneven structure 30 are not covered with the mask 42 in the vicinity of the boundary B corresponding to the inner wall surface 42a of the opening of the mask 42. That is, in the left side of fig. 16, the inner wall surface 42a of the opening portion of the mask 42 is formed so as to bypass the lower end portion of the convex portion 32 formed in a substantially conical shape.

As shown in the upper view of the left side of fig. 16, the inner wall surface 42a of the mask 42 is recessed toward the inside of the mask 42 by a portion that bypasses the convex portions 32 than a portion between adjacent convex portions 32. In this state, when etching is performed to form the through hole 21, the portion of the mask 42 not provided with the convex portion 32 is removed in the depth direction by the etching in the vicinity of the boundary B. On the other hand, the portion protected by the mask 42 is not removed. Therefore, in the vicinity of the boundary B, portions corresponding to the plurality of projections 32 are etched in the depth direction, and the inner wall surface 21B of the through-hole 21 is formed with the stripe-shaped groove 24 having a width almost corresponding to the width of the projection 32 and extending in the depth direction. In this manner, in the example of fig. 16, since the inner wall surface 42a of the mask 42 is formed so as to bypass the plurality of convex portions 32, the groove 24 is formed in the inner wall surface 21b of the through-hole 21 by the difference in erosion rate between the portion covered with the mask 42 and the portion where the convex portion 32 not covered with the mask 42 is present.

The example of fig. 17 represents the following case: when the mask 42 is formed on the substrate 10, half of the plurality of projections 32 of the fine uneven structure 30 is covered with the mask 42 in the vicinity of the boundary B corresponding to the inner wall surface 42a of the opening portion of the mask 42. That is, as shown by the boundary B in the left view of fig. 17, the inner wall surface 42a of the opening portion of the mask 42 is formed in a straight line in a plan view. In this case, a part of the conical projection 32, in this example, a half of the projection 32 is covered with the mask 42. On the other hand, the remaining portions of the convex portions 32 become exposed portions not covered with the mask 42. In this state, when etching is performed to form the through hole 21, the portion corresponding to the exposed portion of the convex portion 32 not covered with the mask 42 first starts erosion from the convex portion 32 in the vicinity of the boundary B, and after the convex portion 32 is eroded, erosion in the depth direction that contributes to the formation of the through hole 21 starts. On the other hand, the portion not provided with the convex portion 32 starts erosion in the depth direction contributing to formation of the through hole 21 from immediately after the start of etching. In this manner, in the vicinity of the boundary B, the portion where the convex portion 32 is not provided is eroded faster by etching than the portion where the convex portion 32 is provided. Therefore, the portion having a high erosion rate is a stripe-shaped groove 24 having a width almost corresponding to the interval of the convex portions 32 and extending in the depth direction in the inner wall surface 21b of the through-hole 21. In the example of fig. 17, the groove 24 is formed in the inner wall surface 21B of the through-hole 21 by the difference in erosion rate between the portion where the convex portion 32 exists and the portion where the convex portion 32 does not exist in the vicinity of the boundary B corresponding to the inner wall surface 42a of the mask 42.

As described above, the reason why the stripe-shaped grooves 24 are formed on the inner wall surface 21b of the through-hole 21 as shown in fig. 15 is due to the interaction between the plurality of projections 32 of the fine uneven structure 30 and the mask 42.

It is considered that a state in which the mask 42 is not formed in the convex portion 32 of the fine uneven structure 30 as shown in fig. 16 and a state in which a part of the convex portion 32 is covered with the mask 42 as shown in fig. 17 are mixed in the boundary B corresponding to the inner wall surface 42a of the actual mask 42. In both the example of fig. 16 and the example of fig. 17, a plurality of stripe-shaped grooves 24 are formed in the inner wall surface 21b of the through-hole 21 in the depth direction by the interaction between the plurality of projections 32 of the fine uneven structure 30 and the mask 42. Therefore, in the present manufacturing step, the width of the stripe-shaped grooves 24 formed in the inner wall surface 21b and the formation interval of the grooves 24 vary depending on the width of the convex portions 32 of the fine uneven structure 30 and the interval of the convex portions 32 as described above.

As a method for forming a concave portion having a high aspect ratio with respect to a substrate, etching by a so-called Bosch Process (Bosch Process) in which an etching gas and an etching protective gas are used alternately in the dry etching step may be performed. According to the bosch process, a through hole having a high aspect ratio can be efficiently formed. Further, it is known that when a through hole is formed by a bosch process, stripe-shaped grooves called "Scallops" (wells) extending in a direction substantially perpendicular to a depth direction are formed on an inner wall surface of the through hole and overlap each other in the depth direction.

As described above, by forming the through-holes 21 in the surface having the fine uneven structure 30 on the surface thereof by the bosch process, the stripe-shaped second grooves 24b intersecting the depth direction substantially perpendicularly can be formed in addition to the stripe-shaped first grooves 24a in the depth direction shown in fig. 15 described above. That is, as shown in fig. 18, a first groove 24a indicated by gray hatching and a second groove 24b indicated by diagonal hatching in the lower right are formed on the inner wall surface 21b of the through-hole 21 in a lattice shape. In this case, in the portion where the gray hatching and the hatching of the lower right diagonal line overlap in fig. 18, the first groove 24a and the second groove 24b overlap each other to form a portion where the groove depths are added to each other to form a deeper groove, and the average period of the second groove 24b in which the uneven portion having a complicated shape is formed can be controlled by adjusting the switching time between the etching gas and the etching protective gas.

Further, by performing the mask forming step and the dry etching step using a substrate having no fine uneven structure on the surface and performing etching by the bosch process in the dry etching step, it is possible to form the through-hole 21 having no first grooves 24a in a stripe shape in the depth direction and having only second grooves 24b in a stripe shape almost perpendicular to the depth direction as shown in fig. 6.

< mask removal Process >

Finally, as shown in ST4 of fig. 10, in the mask removal step, the mask 42 remaining after the dry etching step is removed by spraying the stripping liquid 60 onto the substrate 10. The mask removal preferably includes a dry etching process or a cleaning process using hydrogen peroxide sulfate.

The dry etching step for removing the mask is, for example, a step of performing etching by switching to an etching gas having high etching properties with respect to the mask after the dry etching step for forming the concave portion. The removal of the mask by dry etching can be switched from a step of etching the substrate only by switching the gas to a mask removal step, and therefore, the work efficiency is high.

In addition, if the cleaning step using hydrogen peroxide sulfate is used, the mask 42 remaining after the dry etching step for forming the recessed portion can be effectively removed with a high cleaning force.

Through the above steps, the optical component 1 shown in ST5 of fig. 10 can be obtained.

Hereinafter, an experiment in which the recess is formed in the substrate by the above-described manufacturing method and the stripe-shaped groove is formed in the through hole which is the wall surface of the recess will be described.

Using a silicon wafer as a substrate to be processed, a substrate having a fine uneven structure on the surface thereof is first produced. Specifically, first, an aluminum thin film is formed on the surface of a substrate to be processed by a sputtering method. The thickness of the aluminum thin film was set to 10nm. Thereafter, the substrate was immersed in boiling pure water for 3 minutes as a hot water treatment, thereby changing the aluminum thin film into a fine uneven layer containing an alumina hydrate. Then, ar gas and CHF are used from the surface of the fine uneven layer ₃ Performing penetration treatment with mixed gas of SF ₆ Gas and CHF ₃ The mixed gas of the gases is subjected to reactive ion etching, thereby forming a fine uneven structure on the surface of the substrate to be processed. In this way, a substrate having a fine uneven structure on the surface was obtained.

Then, a photoresist is applied to the fine uneven structure of the substrate having the fine uneven structure on the surface, and an exposure mask having a predetermined opening is disposed on the photoresist to perform laser exposure of the photoresist. Then, by performing the development treatment, a mask having an opening pattern is formed. Thereafter, SF is performed using the mask ₆ Gas and CHF ₃ The mixed gas is used as an etching gas to perform reactive ion etching, thereby forming a concave portion on the surface of the substrate.

Finally, a sulfuric acid hydrogen peroxide clean is performed, removing the mask.

Fig. 19 is an SEM image showing a part of the structure manufactured as described above. As shown in fig. 19, the structure has a plurality of concave portions on the surface of the substrate. The opening of the recess was square with a side of 20 μm. Here, a recess having a depth of 10 μm was formed.

Fig. 20 is an SEM image in which an inner wall surface portion of one recess in fig. 19 is enlarged, and fig. 21 is an SEM image in which an upper portion of the inner wall surface of fig. 20 is further enlarged. As is clear from fig. 20 and 21, a fine uneven structure is formed on the surface of the substrate. As is clear from fig. 21, stripe-shaped grooves (portions observed in a relatively dark color in an image) are formed on the inner wall surface of the recess in accordance with the fine uneven structure on the surface.

Thus, according to the above-described manufacturing method, an optical component having a stripe-shaped groove on the inner wall surface of the through-hole can be obtained.

The entire disclosure of japanese patent application No. 2020-055018, filed on 25/3/2020 is incorporated by reference into this specification.

All documents, patent applications, and technical standards described in the present specification are incorporated by reference into the present specification to the same extent as if each document, patent application, and technical standard incorporated by reference was specifically and individually described.

Claims

1. An optical component, comprising:

a single-layer substrate having a plurality of through holes for transmitting light; and

and an antireflection structure formed on at least a part of an inner wall surface of the through hole and including a plurality of grooves in a stripe shape.

2. The optical component of claim 1,

the groove at least comprises: a plurality of first grooves in a stripe shape along a depth direction of the through hole.

3. The optical component of claim 1,

the groove at least comprises: and a plurality of second grooves in a stripe shape extending in a direction intersecting with a depth direction of the through-hole.

4. The optical component of claim 2,

the tank further comprises: and a plurality of second grooves in a stripe shape extending in a direction intersecting with a depth direction of the through-hole.

5. The optical component of claim 4,

an average period of the plurality of first slots is different from an average period of the plurality of second slots.

6. The optical component according to any one of claims 1 to 5,

the substrate is an opaque material.

7. The optical component according to any one of claims 1 to 6,

the aspect ratio, which is the ratio of the depth of the through-hole to the size of the opening, is greater than 20.

8. The optical component according to any one of claims 1 to 7,

the size of the opening of the through-hole is larger than the average period of the groove.

9. The optical component according to any one of claims 1 to 8,

the size of the opening of the through hole is 5 to 100 μm.

10. The optical member according to any one of claims 1 to 9, comprising a plurality of the through holes, wherein the plurality of holes are arranged in a square array.

11. The optical component according to any one of claims 1 to 10,

the difference between the transmittance of the substrate for the light and the transmittance of the through hole for the light is 70% or more.

12. The optical component according to any one of claims 1 to 11,

the through hole is filled with a transparent material.

13. The optical component according to any one of claims 1 to 12,

the groove is provided in at least one open end of the through hole.

14. The optical component according to any one of claims 1 to 13,

the anti-reflection structure is an irregular structure.

15. The optical component according to any one of claims 1 to 14,

a fine uneven structure having an antireflection function is formed on at least one of the front surface and the back surface of the substrate, except for the opening of the through hole.

16. The optical component of claim 15,

the fine concave-convex structure is an irregular structure.

17. The optical component of claim 15 or 16,

the substrate is provided with a protective layer on a surface on which the fine uneven structure is formed.

18. An optical component in accordance with any one of claims 15 to 17,

the groove of the antireflection structure has a depth deeper than a depth of the concave portion of the fine uneven structure.

19. The optical component of any one of claims 1 to 18,

the substrate is silicon.